LibGL: Implement glDepthRange

Userland/Libraries/LibGL/GL/gl.h

@@ -369,6 +369,7 @@ GLAPI void glColorPointer(GLint size, GLenum type, GLsizei stride, const void* p
 GLAPI void glTexCoordPointer(GLint size, GLenum type, GLsizei stride, const void* pointer);
 GLAPI void glDrawArrays(GLenum mode, GLint first, GLsizei count);
 GLAPI void glDrawElements(GLenum mode, GLsizei count, GLenum type, const void* indices);
+GLAPI void glDepthRange(GLdouble nearVal, GLdouble farVal);
 
 #ifdef __cplusplus
 }

Userland/Libraries/LibGL/GLContext.h

@@ -74,6 +74,7 @@ public:
     virtual void gl_color_mask(GLboolean red, GLboolean green, GLboolean blue, GLboolean alpha) = 0;
     virtual void gl_get_booleanv(GLenum pname, GLboolean* data) = 0;
     virtual void gl_get_integerv(GLenum pname, GLint* data) = 0;
+    virtual void gl_depth_range(GLdouble min, GLdouble max) = 0;
 
     virtual void present() = 0;
 };

Userland/Libraries/LibGL/GLUtils.cpp

@@ -119,3 +119,8 @@ void glDisableClientState(GLenum cap)
 {
     g_gl_context->gl_disable_client_state(cap);
 }
+
+void glDepthRange(GLdouble min, GLdouble max)
+{
+    g_gl_context->gl_depth_range(min, max);
+}

Userland/Libraries/LibGL/SoftwareGLContext.cpp

@@ -1641,6 +1641,18 @@ void SoftwareGLContext::gl_draw_elements(GLenum mode, GLsizei count, GLenum type
     glEnd();
 }
 
+void SoftwareGLContext::gl_depth_range(GLdouble min, GLdouble max)
+{
+    APPEND_TO_CALL_LIST_AND_RETURN_IF_NEEDED(gl_depth_range, min, max);
+
+    RETURN_WITH_ERROR_IF(m_in_draw_state, GL_INVALID_OPERATION);
+
+    auto options = m_rasterizer.options();
+    options.depth_min = clamp(min, 0.f, 1.f);
+    options.depth_max = clamp(max, 0.f, 1.f);
+    m_rasterizer.set_options(options);
+}
+
 // General helper function to read arbitrary vertex attribute data into a float array
 void SoftwareGLContext::read_from_vertex_attribute_pointer(VertexAttribPointer const& attrib, int index, float* elements, bool normalize)
 {

Userland/Libraries/LibGL/SoftwareGLContext.h

@@ -84,6 +84,7 @@ public:
     virtual void gl_color_mask(GLboolean red, GLboolean green, GLboolean blue, GLboolean alpha) override;
     virtual void gl_get_booleanv(GLenum pname, GLboolean* data) override;
     virtual void gl_get_integerv(GLenum pname, GLint* data) override;
+    virtual void gl_depth_range(GLdouble min, GLdouble max) override;
     virtual void present() override;
 
 private:
@@ -215,7 +216,8 @@ private:
             decltype(&SoftwareGLContext::gl_tex_parameter),
             decltype(&SoftwareGLContext::gl_depth_mask),
             decltype(&SoftwareGLContext::gl_draw_arrays),
-            decltype(&SoftwareGLContext::gl_draw_elements)>;
+            decltype(&SoftwareGLContext::gl_draw_elements),
+            decltype(&SoftwareGLContext::gl_depth_range)>;
 
         using ExtraSavedArguments = Variant<
             FloatMatrix4x4>;

Userland/Libraries/LibGL/SoftwareRasterizer.cpp

@@ -260,6 +260,8 @@ static void rasterize_triangle(const RasterizerOptions& options, Gfx::Bitmap& re
 
                         auto barycentric = FloatVector3(coords.x(), coords.y(), coords.z()) * one_over_area;
                         float z = interpolate(triangle.vertices[0].z, triangle.vertices[1].z, triangle.vertices[2].z, barycentric);
+                        z = options.depth_min + (options.depth_max - options.depth_min) * (z + 1) / 2;
+                        
                         if (z >= *depth) {
                             pixel_mask[y] ^= 1 << x;
                             continue;

Userland/Libraries/LibGL/SoftwareRasterizer.h

@@ -29,6 +29,8 @@ struct RasterizerOptions {
     GLenum blend_source_factor { GL_ONE };
     GLenum blend_destination_factor { GL_ONE };
     u32 color_mask { 0xffffffff };
+    float depth_min { 0 };
+    float depth_max { 1 };
 };
 
 class SoftwareRasterizer final {